锥栗贮藏温度对淀粉降解速率的影响

研究了3个不同锥栗品种在1，5，10℃等不同温度下贮藏120 d，并研究了贮藏过程淀粉含量的变化和淀粉降解速率，将降解速率与贮藏温度、品质变化和贮藏时间相关联，建立了锥栗贮藏方程。根据该方程，淀粉的含量随贮藏时间和贮藏温度的提高而降低，在试验范围内，低温度效果比高温度效果好。锥栗的品质与贮藏时间、贮藏温度和品种有关。     

平菇不同温型品种筛选试验

以平菇品种99为对照,对引进的4个平菇品种在不同温度区间进行出菇试验。结果表明,4155、4142在出菇温度为10～25 ℃时随着栽培温度的升高出菇提前,朵形增大,商品性好,生物学效率提高;最适出菇温度为20～25 ℃,此条件下生物学效率分别为133.90%、131.21%。4195、99的最适出菇温度为15～20 ℃,生物学效率分别为113.14%、110.62%。4513在15～25 ℃条件下生物学效率较高。     

贮藏时间和贮藏温度对油菜薹营养品质的影响

为明确不同冷藏时间和不同低温处理对油菜薹营养品质的影响,以2个油蔬两用型油菜品种浙油51和浙油杂108为材料,以新鲜菜薹为对照,设置3个贮藏时间(4℃条件下贮藏1、2、3 d)和3种贮藏温度(-20、-40、-80℃贮藏10 d),分析贮藏期间油菜薹糖类、维生素、纤维素和木质素等含量的变化。结果表明,4℃条件下,随着贮藏时间的延长,两品种中的维生素C和维生素B₁含量均呈现先上升后下降的趋势,维生素B₆、果糖、蔗糖和纤维素含量则逐渐升高;维生素E含量在浙油杂108中呈上升趋势,而在浙油51中呈先上升后下降的趋势;淀粉含量在两品种中变化趋势相同,均为逐步降低。油菜薹石蜡切片结果显示,浙油51中纤维素面积和浙油杂108中木质化面积随贮藏时间的延长而增加。不同贮藏温度下,除纤维素外各营养成分含量均在新鲜状态下最高,纤维素含量则在-20℃下达到最大;两品种的果糖、蔗糖和纤维素含量在-80℃下可达新鲜水平,而浙油51中维生素B₁和维生素E含量则在-40℃下保存更好。综上所述,油菜薹在4℃下贮藏,货架期以2 d为宜;低温下,-40和-...     

长链两性修饰土对Cd2＋的吸附动力学

以两性表面修饰剂十八烷基二甲基甜菜碱（BS-18）修饰的塿土土样为研究对象,在Cd2＋单一条件和与苯酚共存的复合条件下,通过不同的速度参数研究了修饰土样对Cd2＋的吸附动力学特征,并对吸附机制进行探讨。结果显示,在20℃和40℃温度下单一、复合两种处理的条件下,不同修饰比例BS-18修饰土样的各速度参数均大于未修饰土样,且总体上均随着修饰比例的增加而增大,表明修饰可以显著加快塿土土样对Cd2＋的吸附速度;吸附反应分为快速反应和慢速反应2个阶段,总反应平均速度Vt由快速吸附反应速度Vf和慢速吸附反应速度Vs共同决定;温度升高,单一处理Cd2＋的总反应平均速度基本不变,复合处理则下降;加入苯酚可以加快Cd2＋的总反应平均速度,40℃时则表现为抑制效应。Cd2＋吸附速度的描述以双常数方程动力学模型为最佳模型,模型参数A、B值可以用来描述吸附速度的大小。     

水稻爆腰增率与干燥条件关系的试验研究

在各种干燥条件下（包括热空气的温度、湿度、干燥时间）进行了水稻的爆腰率试验。以干燥常数Ｋ为媒介,建立了干燥条件与水稻干燥爆腰增率Ｃ之间的数学模型：Ｃ＝６．６４９＋０．４５３ｔ＋（６．７４９＋０．１５０ｔ）［１．７４６－０．０３９（ＲＨ）－５７．９７４／Ｔ］。结果表明模型预测值与实验测定值相吻合。     

超声辅助萃取芒果叶中芒果苷提取条件优化

为优化芒果叶中芒果苷的提取条件,以溶剂用量、超声时间、超声温度和超声功率为考察因素,采用单因素试验和正交试验对提取条件进行优化;在优选出的超声萃取条件下测定了6个品种芒果叶中芒果苷的含量,并与常规浸渍提取法进行对比。结果表明,超声波辅助提取芒果叶中芒果苷时,影响提取效果大小的顺序依次为溶剂用量超声温度超声功率超声时间;用超声波辅助提取芒果苷的最优组合为:样品量1.0 g,乙醇用量20 mL,超声时间40 min,超声温度50 ℃,超声功率160 W;超声萃取法不但缩短了提取时间,还提高了提取效率,与浸渍提取法相比,超声萃取提取芒果苷量增加了21.60%～26.69%。     

苦瓜活性成分提取工艺研究

通过单因素实验(提取温度、提取时间、料液比和乙醇浓度)和正交试验探索苦瓜皂甙提取的最佳工艺条件。结果表明,苦瓜皂甙提取的最佳工艺条件为:提取温度70℃,提取时间3 h,料液比1∶20,乙醇浓度90%,在此条件下提取的苦瓜活性成分-皂甙粗提物含量最高。     

海参最佳对流干燥温度的研究

该文对海参在不同温度(30、45、60、75、90℃)下的对流干燥过程及特性进行了研究，并对干燥完成后复水海参的流变学性质进行了分析，以得出干燥效率高、干燥后复水品质均较优的海参干燥条件。结果表明：海参干燥过程中水分扩散起主导作用，因此干燥过程仅经历降速阶段；30℃条件下海参干燥效率最低，消耗时间最长；在45～90℃之间，海参干燥速率较高，完成干燥所需的时间较短且相差不大。从干燥后海参的复水效果、流变学性质及感官评价的结果分析，温度高于45℃，海参复水倍数相对较高，且45～75℃条件下得到的海参感官评价结果较佳。综合考虑到海参品质及能耗的要求，以45℃为最佳的干燥条件。     

抽穗期高温对水稻叶片光合特性和干物质积累的影响

以不同温度胁迫下(35℃/3d、35℃/5d、38℃/3d和38℃/5d)的水稻田间试验为基础,研究抽穗期高温胁迫对两个水稻品种扬稻6号和南粳43的干物质积累和分配、叶片绿色度值(Soil and plant analyzer development,SPAD)和净光合速率的影响.结果表明,与常温对照(CK)相比,高温胁迫下,两个水稻品种干物质积累量、SPAD值和净光合速率显著下降(P＜0.05),茎鞘物质输出率和转运率显著增加(P＜0.05).随着胁迫温度的升高和胁迫时间的延长,两个水稻品种各指标的变化幅度逐渐增加.不同水稻品种对高温胁迫的反应不同,扬稻6号受高温影响要小于南粳43.     

不同贮藏条件对芒果干色泽的影响

为了研究芒果干在不同贮藏条件下的色泽变化,通过单因素试验,测定不同温度与光照条件下芒果干的色度值。结果表明,光照对芒果干褐变的影响程度要大于温度。芒果干光照贮藏在10℃时90 d后总色差ΔE为12.06,避光贮藏在30℃时90 d后总色差ΔE为7.02,均出现明显的色泽变化。因此避光及低温贮藏是保持芒果干色泽的理想条件。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.